1. Field of the Invention
The present invention relates to a novel vehicular lamp and, more particularly, it relates to an improved vehicular lamp having a ventilation system including an air communication hole for communicating a lamp chamber with the atmosphere to prevent a lens and a reflecting surface from getting fogged, so that air smoothly flows in and out and water is difficult to enter the lamp chamber.
2. Related Art
There has been known a conventional vehicular lamp having a ventilation system including a communication hole for communicating a lamp chamber with the atmosphere to prevent a lens and a reflecting surface from getting fogged.
FIG. 1 shows an example of a conventional vehicular lamp a1 of this type.
As shown in FIG. 1, a lamp body b1 includes a front opening which is covered with a lens c1 to thereby form a substantially tightly closed lamp chamber d1. A bulb e1 is disposed within the lamp chamber d1 and mounted to the lamp body b1.
A communication hole f1 is formed in the rear wall of the lamp body b1, and a cylindrical communication pipe g1 is provided backwardly from the peripheral edge of the communication hole f1. A water preventive pipe h1 has an almost L-shaped side surface and one end portion of the water preventive pipe h1 connects to the communication pipe g1 in such a manner that it is fitted over the communication pipe g1.
In the conventional vehicular lamp a1, air flows into the lamp chamber d1 from the waterproof pipe h1 through the communication hole f1, which is intended to prevent the lens c1 an the like from getting fogged. Since the waterproof pipe h1 having an almost L-shaped side surface is mounted over the communication pipe g1, water coming from the outside is difficult to enter the lamp chamber d1.
However, the conventional vehicular lamp as described above suffers from a problem that the number of parts is large and the manufacturing cost is rather expensive because it requires the separate waterproof pipe h1.
In view of the above, there is proposed another vehicular lamp a2 as shown in FIG. 2.
In the vehicular lamp a2 shown in FIG. 2, a communication hole f2 is formed in the rear wall of a lamp body b2, an upper wall i2 extends backwardly from an upper edge of the communication hole f2, a couple of side walls j2, j2 (only one of which is shown in FIG. 2) respectively extend downwardly from the right and left side edges of the upper wall i2 and have front edges formed continuous with the rear surface of the lamp body b2, and a ventilation passage m2 is formed. The ventilation passage m2 includes an upper edge formed continuous with the near edge of the upper wall i2, right and left side edges respectively communicating with the communication hole f2 due to a rear wall k2 formed continuous with the rear edges of the side walls j2, j2 and extending in the vertical direction, and an open lower end l2.
Due to the above-mentioned structure, a lamp chamber d2 defined by the lamp body b2 and lens communicates with the atmosphere through the communication hole f2 and ventilation passage m2.
Further, there is proposed another conventional vehicular lamp a3 having a ventilation system in which a cylindrical member n3 is provided in the rear wall of a lamp body b3 in such a manner that it projects backwardly, while the interiors of the cylindrical portion n3 are separated into upper and lower portions p3 and q3 by a partition wall o3. An orifice-like communication hole f3 is formed in a portion of the rear wall of the lamp body b3 that is disposed in the front end of the upper portion p3 of the cylindrical member n3.
As shown in FIG. 3, a backwardly facing stepped portion r3 is formed in the portion of the outer peripheral surface of the cylindrical member n3 located near the rear end of such outer peripheral surface.
Further, there is formed an opening s3 at a position near the front end of such wall of the cylindrical portion n3 as defines the lower side of the lower portion q3. An enclosing wall t3 projects downwardly from the lower surface portion of the cylindrical member n3 in such a manner that it encloses an opening s3.
As shown in FIG. 3, a cylindrical cap u3 having a closed rear end is mounted onto the rear end portion of the cylindrical member n3 in such a manner that it is fitted over the rear end portion of the cylindrical member n3. While mounting the cap u3, the front end of the cap u3 contacts to the stepped portion r3 so that the position of which is thereby defined and, in this condition, a closed wall v3 provided in the rear end of the cap is spaced apart backwardly from the rear end of the cylindrical member n3.
Thus, there is formed a ventilation passage in such a way from the communication hole f3.fwdarw.the upper portion p3 of the cylindrical member n3.fwdarw.the space between the rear end of the cylindrical member n3 and the closed wall v3 of the cap u3.fwdarw.the lower portion q3 of the cylindrical member n3.fwdarw.the opening s3 of the cylindrical member n3, and the lamp chamber d3 communicates with the atmosphere through the ventilation passage.
On the other hand, in solving the above problems, as disclosed in Unexamined Japanese Utility Model Publication No. Sho. 60-84003, there is disclosed such a vehicular lamp a4 as shown in FIG. 4.
In the vehicular lamp a4, a communication hole f4 is formed in the rear wall of a lamp body b4 formed of synthetic resin, while an upper wall i4 extending backwardly from the upper edge of the communication hole f4, tow side walls j4, j4 (only one of them is shown in FIG. 4) respectively extending downwardly from the right and left side edges of the upper wall i4 and including their respective front edges formed continuous with the back surface of the lamp body b4, and a lid member k4 including an upper edge formed continuous with the rear edge of the upper wall i4 cooperate together in defining a ventilation passage m4 which is in communication with the communication hole f4, extends in the vertical direction and includes an open lower end l4.
Here, the lid member k4 is formed integrally with the upper wall i4 through a thin hinge portion n4. The lid member k4, as shown by two-dot chained lines in FIG. 4, is projected backwardly and is then bent substantially at right angles in the hinge portion n4 to be brought into contact with the rear ends of the side walls j4, j4. In this contact state, the lid member k4 and the side walls j4, j4 are welded together to thereby fix the lid member k4 to the side walls j4, j4.
Therefore, a lamp chamber d4, which is defined by the lamp body b4 and a lens, communicates with the atmosphere through the communication hole f4 and ventilation passage m4.
Since the vehicular lamp shown in FIG. 2 does not require a separately produced water preventive pipe as in the vehicular lamp al shown in FIG. 1, the manufacturing cost for the vehicular lamp can be reduced. However, for example, if water splashes into the lamp a2 from the opening formed in the lower end portion of the ventilation passage m2, then the splashing water can move up to the communication hole f2 and thus advance into the lamp chamber d2.
In the vehicular lamp a2, there arises another problem that a slide core is necessary to form the lamp a2.
In the vehicular lamp a4 shown in FIG. 4, since there is eliminated the need for use of a separately produced water preventive pipe h1 as in the vehicular lamp a1 shown in FIG. 1 but the lid member k4 is formed integrally with the lamp body b4, the manufacturing cost for the vehicular lamp can be reduced. However, for example, if water splashes and invades into the lamp a4 from the opening formed in the lower end portion of the ventilation passage m4, then the invading water can move up to the communication hole f4 and thus advance into the lamp chamber d4.
Further, in the vehicular lamp a4 shown in FIG. 4, there is employed a simple structure that the lid member k4 contacts to the side walls j4, j4 to thereby form a space for ventilation and, therefore, unless a good sealing condition is obtained between the lid member k4 and the side walls j4, j4 (the degree of close connection between the lid member k4 and side walls j4, j4 is critical especially when the lid member and side walls are respectively formed of synthetic resin), then water or the like is easy to invade into the lamp chamber d4.
On the other hand, in the vehicular lamp a3 shown in FIG. 3, since the ventilation passage thereof is formed in a maze, the splashed water is prevented from invading into the lamp chamber d3. However, the ventilation passage includes a portion which makes a U-turn with a large radius of curvature to thereby obstruct the smooth flow of the air (that is, a portion extending from the upper portion p3 of the cylindrical portion n3 through the space between the rear end of the cylindrical portion n3 and the closed wall v3 of the cap u3 to the lower portion q3 of the cylindrical portion n3), which makes it difficult for the air to flow. Further, in the vehicular lamp a3, since there is necessary the cap u3 that must be manufactured separately, no cost reduction effect can be expected.